They began blaming conservatives and Dallas the day of the assassination. And they're still doing it. Dallas 1963 (New York: Twelve, 2013) by Bill Minutaglio and Steven L. Davis is the latest book to blame the assassination on the "climate of hate"--generated, of course, by conservatives--that permeated Dallas in 1963.
Could you consider that it might have been Johnson?
Roger Stone (former GOP consultant, now a libertarian...no friend of the left) is arguing that in a book just released a month or so ago.
Personally....I think it is Johnson.
And I believe Oswald was in fact a patsy....